Gaseous phase studies of new copper(II) carboxylate complexes with tert-butylamine as potential precursors for chemical vapor deposition (CVD)

Abstract

Copper(II) carboxylate compounds with tert-butylamine of the general formula [Cu2(tBuNH2)2(μ-O2CR)4], where R=CnF2n+1, n=1–6, were synthesized in the reaction of copper(II) perfluorinated carboxylates with tert-butylamine generated in situ from tert-butyl isocyanate. The obtained complexes were characterized in the solid state and in the gaseous phase by electron impact mass spectrometry (EIMS), IR spectroscopy, and thermal analysis with the detection of evolved gases. In addition, during the recrystallization of the [Cu2(tBuNH2)2(μ-O2CC3F7)4] complex the (tBuNH3)+(C3F7CO2)− ion pair was isolated, and its X-ray structure was determined. As a result of a mass spectra analysis, the presence of metallated species in the gaseous phase was revealed. Among the species detected, the pseudomolecular ions [Cu2(tBuNH2)2(μ-O2CR)3]+ were found. The fact confirmed the dimeric structure of the studied complexes with bridging carboxylates and axially N-coordinated amines. TGA studies demonstrated that copper transfer to the gaseous phase occurs at atmospheric pressure, which suggests that the obtained compounds can be promising precursors for chemical vapor deposition. The selected Cu(II) compounds were used in the preliminary CVD experiments, and the conformal copper layers were formed with no additional reducing agents.